"The writer's job is to tell the truth," Ernest Hemingway once said. When he was having difficulty writing he reminded himself of this, as he explained in his memoirs, A Moveable Feast. "I would stand and look out over the roofs of Paris and think, 'Do not worry. You have always written before and you will write now. All you have to do is write one true sentence. Write the truest sentence that you know.' So finally I would write . . .